Semiconductor laser cavity dispersion measurement based on interferometric crosscorrelation of amplified spontaneous emission

The Fourier transform of the interferometric crosscorrelation of amplified spontaneous emission (ASE) is proposed as a general-purpose method for measuring cavity dispersion. The electric field correlation of the ASE from a cavity shows subfringes displaced from the ordinary interferogram by the cavity round-trip time. The cavity transfer function is derived from the subfringe using the Fourier transform. This method is demonstrated on semiconductor devices. It provides a very quick way to measure round-trip group delay dispersion as well as gain across a device’s whole gain band.